Trace sampling of particles may be used to identify particular types or classes of particles. For example, luggage, cargo containers and people may be screened for explosives or contaminants. More particularly; a sample of trace (e.g., microscopic) particles may be collected from an item or individual, and analyzed for properties indicative of explosives or threats. The analysis of particles may be conducted using a variety of techniques, such as mass spectrometry, ion mobility detection, and gas chromatography with chemiluminescence. Some techniques are able to detect only specific types of particles, or specific classes of particles (e.g., particles with specific types of chemical structures).